1. Field of the Invention
This invention relates generally to optical viewing devices and more particularly concerns a disposable endoscope for use in viewing a region within a body cavity or the like.
2. Description of the Prior Art
Instruments which permit visualization of typically inaccessible areas and organs within a patient's body are known. Such optical viewing instruments, or "endoscopes," can often obviate the need for excising specimens from an internal organ of the living body for examination with a conventional microscope. Also, as disclosed in, for example, U.S. Pat. Nos. 3,677,262 to Zukowski and 4,392,485 to Hiltebrandt, endoscopes may further be provided with a means for supporting and guiding surgical instruments within a patient's body.
Structurally, endoscopes typically include a light pipe for illuminating the region to be viewed, at least one lens assembly for focusing and relaying the image of the illuminated object, and a housing for the entire assembly which is structured so as to minimize tissue damage upon examination. Examples of such endoscopes may be found in U.S. Pat. Nos. 3,089,484 to Hett, 3,257,902 to Hopkins, 3,556,085 to Takahashi, 4,267,828 to Matsuo and 4,273,110 to Groux.
There are several drawbacks in the endoscopes of the prior art to which the present invention is addressed, including the expense and complexity of the known optical viewing devices and the corresponding difficulty in volume production. The devices of the prior art incorporate expensive and carefully fabricated ground glass lenses in structures that are complicated and difficult to manufacture. Typically, as in, for example, U.S. Pat. No. 3,257,902 to Hopkins, endoscopes include a rather complicated design so as to correct for axial color aberration. Because of this, it has not been possible to make such endoscopes disposable, i.e. out of plastic materials, or easily produced in quantity.